Study Of Fiber Bragg Grating Liquid Level Sensor

Optical fiber grating sensor has many advantages such as anti-electromagnetic, anti-corrosion,high sensitivity,small size and so on,because of those advantages,it has been used in many fields,and becomes a focus in optical fiber sensing fields.At first,the characteristic and the development tendency of optical fiber sensor were introduced in this thesis,as well as optical fiber grating sensor.And then the development and the application of liquid level measurement technology had been described.So the study of optical fiber grating liquid level sensor was significant.In the optical fiber grating sensor parts,the transfer matrix method was used to analyse the characteristic properties of optical fiber Bragg grating and its strain sensor sensitivity,temperature sensor sensitivity,and introduce the technology which could solve problem of strain and temperature cross-sensitivity.In the design part of optical fiber grating liquid level sensor,an overall planning of the project had been made.On the basis of the mechanical theory of elasticity, through theoretical derivations,the principle of optical fiber grating liquid level sensor which is based on the fixed circular plate diaphragm was got,and the linear relations between liquid level pressure and the offset of optical fiber grating wavelength was obtained,too.On the basic of theoretical analysis,optical fiber grating was combined with the fixed circular plate diaphragm,by measuring the offset of optical fiber grating center wavelength,pressure signal was got which liquid level produced,and then liquid level signal was obtained.The experiment platform was finished on the basis of optical fiber grating liquid level sensor,pressure gauge,wavelength demodulator,the test box of high and low temperature.By the experiment of temperature and strain,the characteristics of optical fiber grating temperature and strain was testified,and the calculation pressure formula of temperature compensation.Through testing major properties of optical fiber grating liquid level sensor,it was proved that optical fiber grating liquid level sensor made in the project had good resolution,linearity,and precision.